The repairs, which are being completed this week, involve expansion joints that were installed as part of a $9.3 million overhaul conducted over the last two years, according to department spokesman Ted Talbot and Wayne Frankhauser of the Maine Department of Transportation’s bridge program.

The joints, which cost about $42,000, enable the overpass bridge to expand and contract as the temperature rises and falls, Frankhauser said.

Earlier this month, state transportation officials determined that the joints on the southbound side had “started to unzip,” Frankhauser said. “These are joints we use all the time.”

He said the problem was not because of a defect with the joints, which were installed by Turner-based Technical Construction Inc.

“It didn’t hold the load we thought it would hold,” he said. “We’ve determined that it’s not the contractor’s responsibility [to address the problem].”

Frankhauser said the problem was the size of the joint and the volume of traffic using the overpass.

The contractor has been hired to reinforce the joint at an estimated cost of $60,000, according to Talbot.

A joint problem on the northbound side also is being addressed, Talbot said. That issue, however, is the result of a design flaw and is being repaired at the consultant’s cost.